> So maybe it could use something akin to a floating-point representation -
> 12 bits of precision, and a few extra bits to indicate the sensitivity of
> any particular pixel.
>
> This isn't a new idea - Pixar experimented with floating-point linear
> response frame buffers back in the '80s, when they were trying to extend
> the dynamic range. It's a reasonable idea for that purpose, especially
> with noise-free synthetic images, but I'm not sure it would out-perform
> a simple 16-bit linear sensor in the real world.
>
>
Given the eye's logarithmic sensitivity to intensity, it actually
make a lot of sense. At least as much as gamma-correct fixed-point. IIRC
some of the linux utilities used in the movie industry for CG stuff
(cinepaint, vips/nip) have support for some of these mini-floating-point
formats. I think the've got 16-bit floats, 24-bit floats, etc.
I really doubt that the dynamic range is the problem of digital
encoding. It really seems to be sensor limitations, judging by the
"shadow noise" of highly-stretched images. You can encode all the way
down, but digitizing noise is still noise.
Now... if the ANALOG SNR could be improved (by say, a
50ISO-designed APS-sized sensor), then there might be some benefit. As it
is, 12 linear bits seems to fit the effective dynamic range at ISO200
pretty well (yielding approx 8-bits of gamma-corrected image).
-Cory
--
*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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